The mum and her husband Sahatorn, from Thailand, chose to have their late daughter's brain cryogenically preserved after her devastating death from brain cancer in 2015, just before her third birthday.
They now hope Matheryn, who was known as Einz to her loved ones, will one day come back to life, as technologies rapidly advance in the future.
Einz, from Bangkok, was diagnosed with the aggressive cancer just months before her tragic death - sparking a determination in her father, Sahatorn, to give her another chance at life.
After months desperately researching ways to save her, he decided their best hope was cryonics - where a whole body or head is frozen using liquid nitrogen, until a way is found to bring them back to life in the future, and cure what they died of.
The couple chose "life-extension" company Alcor in Arizona, US, to carry out the procedure, making their daughter the youngest person ever to be preserved using the technology.
In new Netflix documentary Hope Frozen: A Quest To Live Twice, her parents reveal the heartbreaking story behind their unconventional decision.
Sahatorn and Nareerat decided to try for another baby after their first son, Matrix, expressed his deepest wish for a sibling.
And when it came to meeting his little sister, Matrix says on camera: “I think I cried I was so happy!”
Satahorn adds: "Einz brought us together, the entire family. Everyone had been waiting for her to arrive.”
However, despite the tot appearing healthy for her first two years of life, she one day failed to wake up in the morning - sparking an agonising few months for her family as she fought aggressive brain cancer.
“I wished I could take her place, take her pain away… I’ve always felt nothing bad could happen to her because her mother is here to protect her," Nareerat says.
Einz underwent 10 surgeries, 12 rounds of chemo and 20 rounds of radiation, but was unable to beat the cancer.
Realising there was no hope of curing his daughter, Sahatorn began researching cryonics, in the hopes of convincing his wife that it could offer their daughter a new life in the future.
While there is the option with Alcor to freeze a whole body, which costs around US $200,000 (£155K), you can also just freeze the head and brain, which costs $80,000 (£62K). Sahatorn hoped to pursue the latter option.
“This was the way to keep her… we must keep her," he says.
At first, the whole family were against the idea, and Sahatorn spent months persuading them.
He says in the documentary: "Can we stop the process of dying? Yes. Can you believe that we can stop it? This is want I have to show my family...
“I spent many months trying to persuade my wife before she finally agreed.”
Once convinced, Nareerat eventually says: "We knew in our hearts that she would pass away. She’d gone as far as humanly possible… the doctors admitted that she would not survive.”
The couple began recording videos for their daughter, to hopefully see in the future, while arranging for a team from Alcor to fly to their home in Thailand - to be there when Einz passed away.
The toddler tragically died on January 8, 2015, just before she turned three, with her family surrounding her at home.
For cryonics to be as successful as possible, experts say it's best to begin the freezing process within 60 seconds of when the heart stops beating.
It meant Einz's family watched on as her body temperate was lowered in front of them, before her body was frozen and flown to Arizona.
Cryonics expert Aaron Drake recalls on camera: “As soon as the heart stops beating, we want to start immediately… 60 seconds if possible.”
“To have her back would be the greatest achievement of my life," he says.
But there is a lot of work to do. While a rabbit's brain has been successfully revived after being frozen, experts have yet to find a way of preserving memories and proper brain function.
“We have to wait for better technology to reconnect everything," Sahatorn says.
The couple have since welcomed another daughter, who they have named Einz Einz in memory of her older sibling.